1. Field of the Invention
The present invention relates to an improvement in a tilt steering column unit for vehicles with a memory mechanism. More particularly, it relates to a tilt steering column unit wherein a supporting portion for rotatably supporting a steering shaft is tiltable around tilt pins with respect to a fixed portion fixed to a vehicle body and which incorporates a memory mechanism for storing a position of the supporting portion before it is tilted up.
2. Related Background Art
In the past, while various tilt steering apparatuses have been proposed, and each has had advantages and disadvantages. In order to eliminate the disadvantages of the conventional tilt steering apparatuses, the Applicant proposed an improved technique as disclosed in the Japanese Patent Laid-Open No. 62-103257. According to such technique, an engagement system rather than a fastening system is adopted to connect the supporting portion to the fixed portion, thereby holding a steering wheel positively, and the rigidity of the steering wheel is increased by selecting the position of an engaging system.
However, it was found that there was room for further improvement in the memory mechanism of such tilt steering apparatus.
That is to say, in the tilt steering apparatus disclosed in the above-mentioned Japanese Patent Laid-Open No. 62-103257, a fixed gear member is attached to the supporting portion, whereas a memory member and a movable member are attached to the fixed portion, whereby the returning position of the supporting portion from tilted up position is determined by the engagement between the fixed gear member and the movable gear member, and the set tilt position is stored or memorized by the engagement between the fixed gear member and memory member. When tilted up, the movable gear member is released from the fixed gear member through the medium of an operating lever, and the alteration of the memory position is effected by a select lever.
In this case, since the memory position is memorized or stored in a condition that a portion (pin) of the memory member is engaged by a portion (recess) of the movable gear member, one must pay attention to the positional accuracy of the engagement portion between teeth of the movable gear member and the memory member. However, since it was very difficult to obtain such positional accuracy, thus leaving slight play between the teeth of these members, a good operating feel could not often be obtained. Further, it was difficult to form the proper engagement portion. In addition, if the operating lever is actuated by mistake while the steering wheel is being lifted, there would arise discrepancy in the positions of the memory member and movable gear member, thus making tilt-lock impossible and also making restoration of the members to their normal original positions impossible or difficult.